A great number of different authenticity attributes are known from the prior art.
Know authenticity attributes include, firstly, attributes which can be recognized by the user of the marked object without any special aids or know-how, such as watermarks, see-through registers, visible and feelable relieflike embossings, colored mottling fibers in bank notes, security threads, outline photogravure and other special printing processes, re-reflective symbols, holograms, hologram-like, embossed, printed or laser-engraved tilting effects and special inks and lacquers with a nacreous or metallic effect.
Secondly, there are attributes which only are accessible to the expert or become recognizable with special equipment. This group of authenticity attributes includes special basic materials such as synthetic fibers and linters in bank notes, mottling fibers, inks and lacquers that e.g. become visible in UV light or change their color by chemically reacting with a secret test substance, security threads with microwriting or radioactive labeling, and individual numberings.
With means for authentication or signature, such as check and identity cards, authenticity attributes furthermore used are the photo and signature of the owner of the object, information stored on microchips and individual secret codes, often in conjunction with encryption methods.
Utility model DE-GM 86 12 236 ("Akustiktrager auf Plastikoder Gummizuschnitt") discloses an acoustic carrier wherein an elongate plastic or rubber blank is provided with a sound profile. The sound profile consists of raised and depressed areas extending perpendicular to the longitudinal direction. It can be scanned with the fingernail or a metal foil serving as a pick-up, whereby acoustically perceptible mechanical oscillations are produced. The acoustic carrier is intended for explaining the phenomenon of sound in school instruction.
Further, U.S. Pat. No. 4,121,835 ("Sound Producing Straw") and U.S. Pat. No. 4,631,715 ("Audio Straw and Cup lid") disclose a straw provided with a sound profile and producing acoustic oscillations when pushed through the opening of a beverage cup lid.
U.S. Pat. No. 3,462,157 ("Audible Greeting Card") discloses a talking greeting card having an elongate profiled sound carrier and a scanning apparatus with a scanning needle and diaphragm. Acoustic oscillations are produced by relative motion of sound carrier and scanning apparatus.
U.S. Pat. No. 4,381,558 ("Talking Greeting Card") describes an acoustic carrier in the form of a flat strip ("sound strip") profiled on one side. It is scanned with the fingernail and connected at one end with a greeting card serving as a diaphragm and resonant cavity. U.S. Pat. No. 2,164,663 ("Phonographic Device") and U.S. Pat. No. 2,042,736 ("Talking Device") disclose similar devices for use as advertising media and talking product packages. U.S. Pat. No. 695,159 ("Apparatus for Reproducing Sound") discloses using the sound strip as a doll's voice, with a special scanning apparatus provided instead of the fingernail.
The patent U.S. Pat. No. 2,997,306 ("Book With Talking Pages") finally discloses a book whose pages have an elongate profiled sound carrier. By scanning the sound carrier with a scanning object one sets the pages oscillating audibly. The acoustic information stored on the sound carrier is related in content to the optical information pictured on the page.
In many cases it is important that the user can check the authenticity of the object provided with the authenticity attribute directly without special aids. This applies e.g. to bank notes, identity cards, drugs or computer software. Many known attributes fail to meet this condition and are therefore not fully applicable.
Also, the rapid advances in production and duplicating methods cause the degree of forgery-proofness of most authenticity attributes to decrease constantly so that new authenticity attributes must always be found.
Moreover, the authenticity attribute should often have esthetic appeal, thereby increasing the subjectively perceived value of the object protected by the attribute and simultaneously producing a likewise subjective feeling of security. Examples to be mentioned are the elaborate steel engraving on paper of value and bank notes as well as holograms.